As semiconductor microfabrication employing a lithography process, lithography processes employing ArF excimer laser (wavelength: 193 nm) an exposure system have been intensively studied. A photoresist composition for such lithography process generally contains an acid generator and a resin which varies its solubility for an aqueous alkali solution by the action of an acid.
US2007/122750 discloses a photoresist composition which comprises a resin having structural units represented by the following formulae.
